This invention relates to test equipment for subjecting test objects to random vibration over a wide band of frequency and amplitude.
It has become a common practice in many industries, particularly the electronics industry, to test their products for conditions to which they may be subjected in the course of their use by the customer, in order to anticipate problems that may arise and design the product to better withstand these conditions. One such condition is vibration.
When it is known what kind of vibration the product will encounter in its normal operation, it may be tested at this particular vibration. However, most products are subjected to a wide band of frequency, amplitude and G-level vibration and shock loads in the course of a normal life, and it has been observed that equipment, subject to a large number of low intensity shocks, do not, in general, display the same types of failure as equipment subject to a few relatively large amplitude shocks. Therefore, to discover weaknesses in the support and damping structures that can become manifest at some unpredictable point in the enormous spectrum of vibration which a product might be subjected to in normal use, it has increasingly been regarded as necessary to test the product over a wide band vibration input, generally 0-2000 Hz, over a wide range of amplitude and G-level.
It has been necessary in the past to test equipment on electrodynamic vibration exciters which are the only means heretofore known for producing the range of amplitude and frequency needed for a thorough test of vibration tolerance. However, the electrodynamic vibration exciters are very expensive to purchase and maintain, and the art has long benn in search of a low cost random vibration generator for a tester which provides a full and adjustable range of amplitude and frequency of vibration shocks.